The present invention relates to a frame which has at least two sectional elements which are detachably interconnected and pressed against each other, the inner one being of a double-walled construction and having webs, which connect an inner section part to an outer one, longitudinal channels, longitudinal slots and either vanes or rails, which are separated from each other by the channels, and a bolt is provided which is anchored in one of the longitudinal slots and is rotatably and longitudinally displaceably mounted in the other sectional element and presses the vanes or rails against an end-face on the other sectional element.
In known frames of this kind, sectional parts are interconnected by longitudinally sliding an anchoring member in one of the sections, this anchoring member being anchored in a slot in the other section, and clamping is achieved by longitudinal displacement of the anchoring member. In such frames the sectional parts are not prevented from rotating relative to each other, which is particularly disadvantageous when the frame is being assembled. Even when the sectional parts are very firmly clamped they may slip, and this leads to displacement in the frame and to damage to the surfaces of the sectional parts which are usually anodized.
The fitting of sectional extensions and other parts of the frame is rendered difficult, and often leads to insufficient stability in the known frames.